This invention relates in general to adzing apparatus of the type normally used in railroad crosstie cutting. Adzing machines are used to cut grooves in the top surfaces of crossties that facilitate the proper placement of rails onto the crossties.
Normally the adzing apparatus is moved across the crossties with an adzing head fixed to a rotating vertical shaft, the head having a plurality of cutting bits which contact the top surface of the crossties. The cutting bits are arranged to rotate in a horizontal plane which, due to the rotary action of the adzing head, produces a flat groove in the crosstie when cutting is complete. The cutting bits gradually wear down during use and eventually, after a number of crossties have been cut, the cutting edge becomes unacceptable. In prior art, an operator will rotate the circular cutting bit at this point to present a new cutting edge. This usually is done at the same time to each cutting bit on an adzing head assembly. U.S. Pat. Nos. 3,005,479, 3,486,542 and 4,506,715 illustrate various known adzing apparatus.
The workman must be careful when rotating a partially worn cutting bit so as to rotate only the worn part of the cutting bit out of the cutting position, thereby preserving the maximum amount of unworn cutting edge for a later time. Also, if the cutting bit assembly is not properly tightened after its adjustment, the cutting bit is prone to rotate away from the new cutting edge, causing a rough cutting action and non-uniform grooves.
This invention is aimed at improving the inexact method of changing cutting edges. Utilizing a square or other noncircular cutting bit and mounting fixture, each new cutting edge can be presented to the work piece in the same orientation as the previous cutting edge, easily and accurately. Also a cutting bit shield of similar noncircular shape is fixed to the cutting bit to provide protection for each of the cutting edges. A shield concept applied to a circular cutting bit is known in prior art, as described in U.S. Pat. No. 4,506,715.